1. Field of the Invention
The present invention relates to a sheet feeding device and an image forming apparatus, and more particularly to a sheet cassette of a sheet feeding device including a stacking plate on which recording media such as sheets are stacked.
2. Discussion of the Background
In an image forming apparatus, such as a copier, a printer, a facsimile apparatus and a printing apparatus, an image formed by an image formation part thereof is transferred onto a recording medium such as a recording sheet conveyed from a sheet feeding device, and thereby a record output is obtained.
A cassette in which recording media are stacked is installed in the sheet feeding device, and the sheet feeding device is configured to feed out the recording media in the cassette.
Some cassettes are configured to accommodate recording media of a specific size. In this case, one cassette is necessary for each desired size of recording media, so that the procurement and operating cost of the apparatus is increased. Further, when the image forming apparatus is configured such that one cassette can be installed in the sheet feeding device, when use of a different size of recording media is desired a different cassette must be installed, which is troublesome. Even when the image forming apparatus is configured such that a plurality of cassettes can be installed in the sheet feeding device, often cassettes must be exchanged. Furthermore, because a cassette for recording media of a size that is used infrequently must be also procured, the procurement and operating cost of the apparatus is further increased.
A cassette for use in a sheet feeding device generally includes a stacking plate on which recording media are stacked. A sheet feeding device includes a mechanism to detect a remaining quantity of recording media stacked on a stacking plate. In such a sheet feeding device, the front side of the stacking plate in the feeding direction of the recording media is pushed up, and thereby the uppermost one of recording media stacked on the stacking plate press-contacts a sheet feeding roller serving as a sheet feeding member which is disposed above the stacking plate.
Published Japanese patent application No. 2000-118792 describes a sheet feeding device including a mechanism to detect a remaining quantity of recording media stacked on a stacking plate of a cassette mechanism includes a first detection feeler that is press-moved by an upper surface of the recording media stacked on the stacking plate, and a second detection feeler that is press-moved by the stacking plate when all the recording media stacked on the stacking plate are fed out. A recording media end condition in which all the recording media stacked on the stacking plate are fed out, is detected based on the moved positions of the first and second detection feelers.
Generally, in a sheet feeding device for use in an image forming apparatus, an amount of pushing up a stacking plate of a cassette toward a sheet feeding roller, a contact pressure between recording media stacked on the stacking plate and the sheet feeding roller, and a positional relation between a detection feeler of a recording media remaining quantity detection mechanism and the stacking plate when no recording media are placed on the stacking plate, are preset according to size and thickness of recording media used in an image forming apparatus. In this condition, a cassette needs to be exclusively used in a sheet feeding device of an image forming apparatus, and a cassette cannot be commonly used in different image forming apparatuses. As a result, a production cost and parts management expenses of cassettes increase.
Therefore, to decrease a production cost and parts management expenses of cassettes, it is desirable to provide a sheet feeding device for use in an image forming apparatus that includes a cassette having a configuration in which major parts of the cassette can be commonly used in different image forming apparatuses.